<local:FeedItemViewModel 
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"       
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:RssReader" 
    Description="description1" Title="Post1" Url="http://www.web.com">
    
    
</local:FeedItemViewModel>